In this guide we propose, as an example, the design of a simple supervision application Mitsubishi MELSEC FX protocol based;this example is a little step towards the design of more complex SCADA applications, but it can be useful foranybody who approaches for the first time to a SCADA, and in particular to Winlog Pro 3 software, to quickly understand how to communicate with external devices (Mitsubishi FX PLCs).